Adhesive composition



are in rather extensive use..

Patented Jan. 12, 1943 ADHESIVE COMPOSITION Wesley N. Lindsay, Brooklyn,N. Y., and Harold Charles Li'etz, San Francisco, Caliik, assignors toThe Arabol Manufacturing Company, New York, N. Y., a corporation of NewYork No Drawing. Application August 23, 1940, Serial No. 353,892

3 Claims. (Cl. 106-157) This invention relates to adhesive compositions,and more particularly to improved adhesives of the class containing gelforming protein, commercially termed "iceproof glue.

The adhesive of the present invention is useful for attaching paperlabels and the like to containers, characteristic in that immersion incold water does not disturb the adhesion of the label. Generallyspeaking, the iceproof glue or adhesive is used to attach relativelywater permeable members, such as paper labels or the like, to reusablecontainers such as bottles. The labeled container may be immersed incold or iced liquid over fairly long periods, the label firmly remainingon the bottle, not being removable by ordinary handling. A furthergeneral characteristic of iceproof glue is that a label attachedtherewith may be readily removed from the container by washing with warmwater, even without the use of a detergent.

Iceproof glues are well known in the art and They contain an animal glueor similar gel forming protein in water soluble form, in a concentrationwhich would set to a firm gel in the absence of modify- I ingsubstances. They also contain a highly water soluble substance which maybe termed a gel inhibitor or liquifying agent. The inhibitor or agent isone which does not react with protein or alter its chemical structure torender it incapable of gelation. Its function is to inhibit the gelationor lower the temperature at which gelation occurs. When the agent isremoved from the protein solution it leaves it in such condition thatgel formation thereupon occurs.

The action or operational mechanism of iceproof glue is as follows: Theadhesive film between the label and container contains the solubleprotein and liiquifying agent in combination,

as previously stated. The label becomes permeated with water uponimmersion in cold water. The highly water soluble liquifying agentrapidly dissolves, and difl'uses through the label. The concentration ofliquifying agent in the adhesive film thereupon becomes reduced, andgelation of the protein is no longer inhibited. A gel is formed whichcan only extremely slowly disperse or dissolve in water. properties toadhere the label effectively onto the container. The gel so formed mayhowever be liquiiied by heat. Thus, washing the label at an elevatedtemperature readily efiects a complete and clean removal of the labelfrom the container. 1

Iceproof glue generally contains other ingredients than those mentioned.Starch, dextrine, or other modified starch is generally included toincrease the initial viscosity or tackiness of the glue, and otherwiseimprove its operation with labeling machinery, or the like. It alsodecreases stringiness in the glue. The starch may be added to theadhesive composition in its modified form. On the other hand, it may beadded directly andmodified in the process of manufacturing the adhesive.Another ingredient is generally added to decrease the rate atwhich thedry glue film is permeated and swollen by known to those skilled in theart.

Among gel inhibitors or liquifying agents previously used or proposedfor iceproof glues are calcium chloride, calcium nitrate, magnesiumchloride, sodium chloride, sodium nitrate, urea and lactic acid.However, the prior liquifying agents rendered the iceproof glue eitherso hygroscopic as to present greatly retarded drying rates under highhumidity; or, decreased its iceproofness by permitting the liquifiedprotein to dissolve too rapidly and difiuse through the label.

In accordance with the present invention, the use of a water solublethiocyanate is proposed as the liquifying agent for animal glue gels,and particularly for application in adhesive of the iceproof glue type.We have found that the use of water soluble thiocyanate overcomes thedisadvantages of the prior liquifying agents. The ad- The-gel hassufiicient adhesive v hesive composition of the invention is neither toohygroscopic nor too stable in its liquification. The adhesivecomposition or iceproof glue of the invention contains a water solublethio'cyanate as the liquifying agent, the other ingredients beingsimilar to those of the prior art compositions. We have found that thecomposition of the invention may be readily adapted for, all commercialapplications for such adhesives, re-

2 I maining stable under widely'varying conditio- By way of example. thepositions are given:

The proportions of the ingredients may of course be considerably varied.The procedure of preparing the adhesive composition is similar to thatheretofore practiced, and wellknown by those skilled in the art.Briefly, the animal glue is mixed with the water and allowed to standfor one hour without heating. The mixture is then raised to atemperature of about to C. to complete the dispersion of the glue andthe 'liquifying agent, namely the thiocyanate, is added to the mixtureat about this temperature. The starch which may have been previouslymoistened with a portion of the water component, is then added to themixture at the elevated temperature. The mixture is then agitated andheated in a temperature of to C. and the remaining ingredients of-thecomposition areadded. The resultant adhesive is then strained, ifnecessary, and cooled. In an alternate procedure, the starch is added ina dry state providing the liquified glue mixture is cooled from its 55to 60 C. temperature to about 45 C. to inhibit lumping.

Suitable commercial water soluble thiocyanates are those of ammonium,sodium and potassium, although others may be used. Practical proportionsof the thiocyanate is in the range of 25 to 60 per cent of the dryweight of the glue. Other starches than the tapioca and sago starchesillustrated, may be used; as may dextrines or modified followins typical.corn- Example I Pounds Animal glue (360 gm.) 120 Ammonium thiocyanate50 Tapioca star h 120 Water 259 Phenol 1 Total -L 550 Example]! 1 PoundsAnimal glue (360 gm.)- 105 Sodium thiocyanate 52 Sago star h 105 Water267 Lanolin 20 Phenol 1 Total 550 starches. The characterisation of theanimal -mal glue, gel forming proteins, and gelatin may be used bysuitably varying the formula of the composition to produce the desiredresults. The purified gelatin may be substituted. The protein used musthave gel forming characteristics in aqueous solution which is inhibitedor depressed by the liquifying agent.

Although specific compounds and compositions for practicing theinvention have been described and illustrated, it is to be understoodthat modi-. flcations which fall within the broader spirit and scope ofthe invention may be practiced, and accordingly we do not intend to belimited except as set forth in the following claims.

What we claim is: I

1. An iceproof glue of the character described comprising thecombination of a gel forming protein and starch in substantially equalproportions,

' and a water soluble thiocyanate in the proportion of about 60 per centof the dry weight of said protein to inhibit gel formation of theprotein in the composition, said thiocyanate dissolving out of thecomposition when it is immersed in water to effect gel formation of saidprotein therein.

2. An iceproof glue of the character described comprising thecombination of a protein which disperses in hot water and gels uponcooling, starch substantially equal in amount to said protein, and awater soluble thiocyanate in the proportion substantially in the rangeof about 25 to cent of the dry weight of said protein for inhibiting thegel formation of the protein and gelatinizing and stabilizing dispersionof the starch in the glue. 4

WESLEY N; LINDSAY. HAROLD CHARLES LIETZ.

